Background

Florida's original wetlands engineers are once again working in the state. Moving southward like a very slow cold front, beavers (Castor canadensis) have been making their way from Georgia and Alabama. Beavers are returning to areas they previously occupied, but disappeared from in the 1800s.

Not everyone welcomes their return. In the current human-dominated landscape, beaver activities often conflict with human's. By gnawing trees and damming streams, beavers sometimes create trouble for landowners. However, their ponds and water retention areas provide valuable habitat for fish and wetland wildlife.

Description

Beavers, the largest of all North American rodents, are semi-aquatic, furbearing mammals. Adult animals often weigh 30-50lb (13-22kg) and measure 30in (76 cm) from nose to base of tail.

The most prominent feature of these stocky animals is a flattened, scaly tail. It serves its owner as a prop while sitting up and for propulsion, steering, and communication while swimming. A resounding tail slap on the water surface signals danger.

In addition to webbed hind feet, beavers have other adaptations for aquatic life. Their nose and ears have valves that can be closed when diving. Beavers also are able to close their lips behind their large incisor teeth so they can chew while underwater.

The soft brown fur is groomed and conditioned with oil from paired anal glands. A pair of "castor glands" also empty near the anus. Castoreum, from these glands, functions as a territorial marker: Beavers often build scent mounds, low piles of mud and twigs, which they mark with castoreum.

Distribution and Habitat

Thousands of years before the arrival of European explorers, beavers lived in peninsular Florida, busily creating and recreating wetland habitats. Fossil records at the Florida Museum of Natural History show that beaver habitation once extended as far south as Orange County.

Between 1850 and 1900, beaver populations declined rapidly within the state. Hunting and development share the blame for their demise. By the early 1900s, beavers were absent from all but the northern fringe of Florida

Conservation programs and decreased demand for beaver products allowed populations throughout the United States to slowly rebound. By 1957, beavers had returned to areas west of the Ochlockonee River near Apalachicola. By 1990, their range extended to a line roughly drawn from Levy to Duval Counties.

Florida beavers generally inhabit rivers and streams. They also may be found in springs, sloughs, and lakes. Running water appears to be a favored habitat feature.

These pioneering animals are very opportunistic when building dens. They build according to their geography and the resources of the area. Along low river banks the traditional tepee lodge of sticks and mud may be constructed.

These dens typically have several underwater entrances as a safeguard against predators. In hillier areas, beavers burrow into the bank or create dens under root systems of large trees.

Where limestone outcroppings occur, beavers may use small, natural caves for dens. Some of the more creative ones build a tepee of sticks covering a lime-rock cave or build a lodge around a hollowed cypress stump. Beavers may occupy two or more different style lodges at any one time. They build houses in any area that provides a year-round source of water. To insure adequate water levels for safe and efficient travel, these four-footed engineers also frequently show their skill at dam building.

Natural History

Because of their aquatic lifestyle, Florida beavers have few natural enemies. Man, bobcats, coyotes, and alligators remain their chief predators. Compared to most other rodents, beavers have a relatively long lifespan. Some live more than 10 years.

Reproductive Habits

Little is known about the reproductive habits of Florida beavers. Mating in pairs, they breed between December and February. Two to four young, called kits, are typically born following 100+ days gestation. The young stay with their parents until sexually mature at about age two. So a family unit may consist of parents, two to four yearlings, and the current year's litter.

Diet

Although occasionally seen during daylight hours, beavers usually work through the night feeding and maintaining water levels needed for safe travel and transporting food and building materials.

As vegetarians, beavers have no trouble finding a balanced diet in the abundant and diverse plant life of northern Florida. They may cut down trees up to a foot in diameter and dine on the inner bark, leaves, roots, buds, and twigs. A partial listing of food trees includes willow, gum, cypress, pine, oak, hawthorne, and magnolia. Some other utilized plants are wax myrtle, grape vine, saw palmetto, lizards tail, water lily, and pickerel weed. Beavers even will float leisurely around and scoop large amounts of duckweed into their mouths.

Environmental and Economic Values

Beavers can be beneficial to the environment. By damming streams and creating ponds, beavers create wetland habitat for plants, wildlife, and fish. Because broad expanses of floodplain swamps act as "shock absorbers" for floods, erosion, sedimentation, and surface water runoff, beavers can have positive effects on riverine water quality. Their ponds and canals also provide recreational benefits such as fishing, hunting, wildlife observation, and photography.

Beaver are classified as short-haired, fur-bearing animals because they have short, soft, silky hair covering their bodies. For generations, many people used furs as payment for food and other necessities. Beaver meat was considered a delicacy. But fur farms, changes in fashion perceptions, and increased use of synthetic fibers have lowered the demand for wild furs.

Problems and Control Methods

Human and beaver goals often conflict. Beaver dams may block drainage systems and flood roads, crops, and timberland. Hungry beavers occasionally chew down ornamental trees and venture into fields to feed on crops like sorghum and corn.

Fencing

Where beavers pose problems, several methods may be employed to control damage and local population numbers. Hardware cloth fencing at least 3.5ft (1.2 m) high may prevent damage of valuable trees.

Daily destruction of dams and removal of dam building materials sometimes will cause a beaver colony to abandon an area.

However, most beavers will look at this as an opportunity to polish their construction skills. Fencing, culverts, drain pipes, or similar structures are not very effective and often result in beavers using the fence as a base for their dam.

Water Control

Water control structures inserted into the dam can effectively prevent excessive flooding. Corrugated steel or PVC pipe may be placed in a narrow, deep "V" break in the main channel area of the dam. Some control structures have been constructed out of wood or logs. The material and design are not as important as the placement of the structure. The inflow end should be located near the bottom of the pond (Figure 1), about one foot lower than the outlet end, and at least 6ft (2m) away from the dam to avoid detection and blocking by the beavers.

Figure 1.

The rate of water flow, land elevation, and desired water level also are considerations that must be made prior to placement of the water control structure. Occasional maintenance usually is needed to prevent the pipes from clogging with debris. This method of control offers a way for beavers to passively coexist with people.

Traps and Trapping

The Bailey live trap is another management alternative. This unique suitcase-like trap is used for live-trapping and relocating problem beavers. The problem with relocating any animal, however, is that they might be even more troublesome at their new location.

No known effective beaver repellents or fumigants exist. Poisoning is illegal because of the potential danger to humans and other non-target organisms.

Lethal control methods include shooting and trapping. Although shooting can be an effective way to remove damaging individuals, some local ordinances in urban areas prohibit discharging of firearms. A no-cost permit from your regional Florida Fish and Wildlife Conservation Commission office is required to use a gun and light. A light with a red filter is best because beavers cannot readily detect it.

Steel leg-hold (size No. 2 or larger) and conibear (size 330) traps probably are the most effective control tools, but they are illegal in Florida without a permit. You may obtain a special use, no-cost permit from your regional Florida Fish and Wildlife Conservation Commission office. Wire snares also can be useful in eliminating problem beavers. You must check trap and snare sets at least every 24 hours.

Note: A furbearer license is required to sell beaver pelts. People with beaver problems also should realize that whether an animal is live-trapped and relocated or killed, other beavers may move into the vacated habitat.

Footnotes

1.

This document is WEC17, one of a series of the Wildlife Ecology and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: December 1990 as SS-WIS-17 "Florida Beavers." Revised December 2006. Reviewed March 2013. Visit the EDIS website at http://edis.ifas.ufl.edu.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.